Vegetation, emissions and particles (RA3)

The overall aim of RA3 is to formulate and validate a model framework linking vegetation, aerosols, clouds and their climate feedbacks, using a combination of laboratory studies, field studies and modelling. Process parameterizations are tested in process models and air quality chemical transport models such as the EMEP for evaluation with field observations, then to be included in climate models.

Close up of soot particle, photographer: Arash Gharibi

Aerosol particles and their role for clouds and climate is in addition to an important part of climate research also of huge importance for air quality around the world. The concept of short-lived climate pollutants including particles are on the political agenda as illustrated for example by the formation of the he Climate and Clean Air Coalition. The terrestrial carbon cycle and aerosol–cloud–climate interactions are key components in the climate system, but they are complex to describe in climate models. The complexity is further compounded by the fact that the biosphere, clouds and particles are related through important feedback processes.

RA3 focuses in particular on the representation of the C and N cycles, emissions of biogenic volatile organic compounds (BVOCs) and N-based trace gases from ecosystems, the subsequent atmospheric oxidation of BVOCs and their secondary organic aerosol (SOA) formation potential, with consequences for clouds, global radiation and precipitation. This RA utilizes laboratory set-up, fled observation station and various models as described below.

Model development

The main goal of RA3 is to utilize laboratory and field observations in order to strengthen and develop models. Three parallel model-development approaches are applied. Detailed chemical and aerosol processes are tested in process models where explicit formulations can be used. Examples of such models are box models based on MCM (Master Chemical Mechanism) or similar chemical schemes linked to some dynamic aerosol particle representations often based on information from laboratory work. These schemes can either be used explicitly or reduced for field-model comparison. Currently, three models are developed within MERGE. The ADCHEM model is tested in Lagrangian model, the Ecosystem surface exchange (ESX) 1-D model is developed for within canopy modeling alongside the 3-D EMEP model; this EMEP model will be used to test improved biosphere components and their impact on air quality and aerosols over Europe. RA3 is also, together with RA1, taking part in the development of particle representation in the EC-Earth model.

Laboratory work

Flow reactors and chambers are used to test reaction mechanisms and aerosol processes, while larger oxidation chambers and the access to European infrastructures within strategic research collaboration, e.g. the Plan chamber in Julich and the SAPHIR chamber, allow to mimick atmospheric conditions. Gases and particle composition and properties can be measured with a unique suite of advanced instrumentation enabling an ensemble of analyses that competes on the highest international level.

Field observations

The group is running the EMEP monitoring station at Vavihill (VHL, 56 01N, 13 09E, 172 m asl.). VHL is a continental background site with no local sources of pollution, situated in the southernmost part of Sweden. It is well suited for studies of the influx of polluted air from continental Europe to the Nordic countries along a south-north transect. VHL is equipped with meteorological instrumentation and can measure gases, aerosol particles, and precipitation chemistry. In addition to the involvement in the monitoring station, RA3 researchers are active in several international measurement campaigns utilizing high competence and advanced instrumentations to study atmosphere-cloud-climate interactions.